1. Field of the Invention
The present invention relates to an image reading apparatus, a default value adjusting method of an image reading apparatus, and a chart original, and in particular, relates to an image reading apparatus having default values of a resolution of a pulse motor that moves a lens unit or the like of the image reading apparatus, a default value adjusting method of an image reading apparatus which adjusts default values, and a chart original which is directly used in an embodiment of the default value adjusting method of an image reading apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-Open (JP-A) No. 5-281631 discloses a method for adjusting a position of a zoom ring which adjusts the magnification of a zoom lens and a position of a focusing ring which adjusts the focusing point of the zoom lens, in accordance with the size of a photographic print. In this method, a default value of the position of the zoom ring and a default value of the position of the focusing ring, in accordance with the size of a photographic print, are recorded in advance in a memory. On the basis of these default values, the position of the zoom ring and the position of the focusing ring are controlled, an image of a photographic print is image-formed (focused) at an image sensor, and the image thus image-formed at the image sensor is displayed on a preview display apparatus. In cases in which the image displayed on the preview display apparatus is not suitable for the display screen, an operator adjusts the respective positions of the zoom ring and the focusing ring such that the image displayed on the preview display apparatus becomes suitable for the display screen, while observing the image displayed on the preview display apparatus. The already stored default value is changed to the value obtained by the adjustment of the zoom lens. As a result, since an adjusted default value in accordance with each of the photographic print sizes thereafter is used, it is not necessary to adjust the zoom lens in accordance with the size of each photographic print. The burden on the operator in terms of time and labor can be reduced.
However, in the conventional adjusting method described above, although the burden on the operator in terms of time and labor is reduced after the default value is adjusted, however, during adjustment, much time is required, since the default value must be adjusted for each size of the photographic film while viewing the display screen.
The present invention has been devised to overcome the above problems. An object of the present invention is to provide an image reading apparatus and a default value adjusting method of an image reading apparatus which reduce the work involved in adjustment. Further, an object of the present invention is to provide a chart original which facilitates detection of positional offset between an original holding portion and an image reading element.
In order to achieve the above object, the image reading apparatus of the present invention comprises:
a reading section movable in an optical axis direction, said reading section including a lens unit which is movable in the optical axis direction, and an image reading element which is disposed at a focusing position of the lens unit and which via the lens unit reads an image of an original disposed at an original reading position;
first driving means for moving the lens unit in the optical axis direction in accordance with an inputted signal of a first pulse number;
second driving means for moving the reading section in the optical axis direction in accordance with an inputted signal of a second pulse number;
storing means for storing a first default value, which expresses an amount of movement corresponding to a unit pulse of the first moving means, and a second default value, which expresses an amount of movement corresponding to a unit pulse of the second moving means; and
pulse number calculating means for calculating the first pulse number corresponding to a focusing magnification by using the first default value, inputting a signal of the first pulse number to the first driving means, calculating the second pulse number corresponding to the focusing magnification by using the second default value, and inputting a signal of the second pulse number to the second driving means.
It is preferable that the image reading apparatus of the present invention be provided with adjusting means which makes the pulse number calculating means calculate a first pulse number and a second pulse number which correspond to a predetermined set focusing magnification, and makes the pulse number calculating means input a signal of the first pulse number to the first driving means and input a signal of the second pulse number to the second driving means so that the lens unit and the reading section are moved, and thereafter,
the adjusting means carries out autofocusing, in which the second driving means is driven so as to carry out focusing with respect to the original, and carries out magnification adjustment, in which the first driving means is driven such that an actual focusing magnification after autofocusing is carried out coincides with the set focusing magnification, until the actual focusing magnification becomes a value which is within a standard range with respect to the set focusing magnification, and
the adjusting means adjusts the second default value on the basis of the second pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a conjugate length for the set focusing magnification, and adjusts the first default value on the basis of the first pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a distance from a principal point of the lens unit to the focusing position with respect to the set focusing magnification.
The adjusting means can adjust the second default value on the basis of a difference in the second pulse numbers with respect to two set focusing magnifications, each of the second pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in conjugate lengths for the two set focusing magnifications, and the adjusting means can adjust the first default value on the basis of a difference in the first pulse numbers with respect to the two set focusing magnifications, each of the first pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in distances with respect to the two set focusing magnifications each of the distances being from the principal point of the lens unit to a focusing position.
It is preferable that the image reading apparatus of the present invention be provided with positional offset detecting means for detecting positional offset between the image reading element and an original holding portion which holds the original at the original reading position, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
In a default value adjusting method of an image reading apparatus of the present invention, the image reading apparatus comprises:
a reading section movable in an optical axis direction, the reading section including a lens unit which is movable in the optical axis direction, and an image reading element which is disposed at a focusing position of the lens unit and which via the lens unit reads an image of an original disposed at an original reading position;
first driving means for moving the lens unit in the optical axis direction in accordance with an inputted signal of a first pulse number;
second driving means for moving the reading section in the optical axis direction in accordance with an inputted signal of a second pulse number;
storing means for storing a first default value, which expresses an amount of movement corresponding to a unit pulse of the first moving means, and a second default value, which expresses an amount of movement corresponding to a unit pulse of the second moving means; and
pulse number calculating means for calculating the first pulse number corresponding to a focusing magnification by using the first default value, inputting a signal of the first pulse number to the first driving means, calculating the second pulse number corresponding to the focusing magnification by using the second default value, and inputting a signal of the second pulse number to the second driving means,
and the default value adjusting method comprising steps of:
making the pulse number calculating means calculate the first pulse number and the second pulse number which correspond to a predetermined set focusing magnification;
making the pulse number calculating means input the signal of the first pulse number to the first driving means and input the signal of the second pulse number to the second driving means so that the lens unit and the reading section are moved;
carrying out autofocusing, in which the second driving means is driven so as to carry out focusing with respect to the original, and carrying out magnification adjustment, in which the first driving means is driven such that an actual focusing magnification after autofocusing is carried out coincides with the set focusing magnification, until the actual focusing magnification becomes a value within a standard range with respect to the set focusing magnification; and
adjusting the second default value on the basis of the second pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a conjugate length for the set focusing magnification, and adjusting the first default value on the basis of the first pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a distance from a principal point of the lens unit to the focusing position with respect to the set focusing magnification.
In the default value adjusting method of the image reading apparatus according to claim 7, wherein the second default value is adjusted on the basis of a difference in the second pulse numbers with respect to two set focusing magnifications, each of the second pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in conjugate lengths for the two set focusing magnifications,
and the first default value is adjusted on the basis of a difference in first pulse numbers with respect to the two set focusing magnifications, each of the first pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in distances with respect to the two set focusing magnifications each of the distances being from the principal point of the lens unit to a focusing position.
The chart original of the present invention is a chart original in which two or more patterns are disposed so as to be separated at predetermined intervals and so as to be symmetric with respect to a second imaginary line which is orthogonal to a first imaginary line, each of the patterns being formed from a first line segment, which is orthogonal to the first imaginary line, and two second line segments, which are disposed at opposite positions with respect to the first line segment so as to intersect the first line segment, and each of the patterns intersecting the first imaginary line at the three points.
In the present invention, the first pulse number corresponding to the focusing magnification is calculated by using the first default value. By inputting a signal of the first pulse number, the lens unit is moved in the optical axis direction by the first moving means. The second pulse number corresponding to the focusing magnification is calculated by using the second default value. By inputting a signal of the second pulse number, the reading section is moved in the optical axis direction by the second moving means. The image of the original, which is disposed at the focusing position of the lens unit and at the original reading position, is read by the image reading element via the lens unit.
In the present invention, when the default value is adjusted, the default value recorded in the storing means are used, the driving means are driven, and the lens unit and the reading section are thereby moved to positions corresponding to the set focusing magnification determined in advance. Thereafter, the second driving means is driven so as to be focussed with respect to the original, and the first driving means is driven such that an actual focusing magnification after autofocusing coincides with the set focusing magnification, until the actual focusing magnification becomes a value within a standard range with respect to the set focusing magnification.
Then, the movement amount corresponding to the unit pulse of the second driving means is calculated, based on the second pulse number of when the actual focusing magnification becomes a value within the standard range with respect to the set magnification, and based on the conjugate length with respect to the set focusing magnification. The second default value recorded in the storing means is changed to the thus calculated value. Further, the movement amount corresponding to the unit pulse of the first driving means is calculated, based on the first pulse number of when the actual focusing magnification becomes a value within the standard range with respect to the set magnification, and based on the distance from the principal point of the lens unit to the focusing position with respect to the setting focusing magnification. The first default value recorded in the storing means is changed to the thus calculated value. As a result, the respective planned positions of the lens unit and the reading section for the focusing magnification coincides with the respective actual positions.
In the present invention, default values can be adjusted using one set focusing magnification. However, the default values can be adjusted with further accuracy in using two set focusing magnifications, by adjusting the second default value on the basis of a difference in second pulse numbers with respect to two set focusing magnifications each of the second pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification and on the basis of a difference in conjugate lengths for the two set focusing magnifications, and adjusting the first default value on the basis of a difference in first pulse numbers with respect to the two set focusing magnifications, each of the first pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification and on the basis of a difference in distances with respect to the two set focusing magnifications each of the distances being from the principal point of the lens unit to the focusing position.
In the present invention, it is preferable to provide a positional offset detecting means for detecting positional offset between the image reading element and an original holding portion which holds the original at the original reading position, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
The positional offset between the original holding portion and the image reading element can be detected by using the chart original of the present invention, in which two or more patterns are disposed so as to be separated at predetermined intervals and so as to be symmetric with respect to a second imaginary line which is orthogonal to a first imaginary line, each of the patterns being formed from a first line segment, which is orthogonal to the first imaginary line, and two second line segments, which are disposed at opposite positions with respect to the first line segment so as to intersect the first line segment, and each of the patterns intersecting the first imaginary line at the three points. The chart original of the present invention is disposed such that the first imaginary line is oriented in a direction corresponding to the direction in which the plural pixels of the image reading element are arrayed. By detecting the intervals between three points intersecting the direction in which the pixels are arrayed, the positional offset between the original holding portion and the image reading element can be corrected.